Bumper reinforcement is known with a closed cross-section structure configured by joining together an inside member and an outside member (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-199293, JP-A No. 6-135290, JP-A No. 2005-271734 and Japanese Utility Model Application Laid-Open No. 2-78451). In such bumper reinforcement structures, structures are known in which plural closed cross-sections are formed from top-to-bottom (see, for example, JP-A No. 2000-198401). Furthermore, in bumper reinforcement, technology is known wherein a web is made thicker on a compression flange side than on a tension flange side of a bending neutral axis of the web (see, for example, JP-A No. 11-59296).